A couple of years ago we did a buildup using the GMPP 572/620. We swapped out the camshaft for the standard H.O. 502 roller and added a Performer RPM to the engine. It had outstanding torque and idle quality, but it did smack us in the horsepower bank. Many couldn't understand why we would want to do that to the 572, but it would have made a killer Power Tour engine. We had to run manifold spacers for that buildup. In the past two years, no manufacturer has stepped up and built a dual-plane inlet, either rectangle- or oval-port manifold, for the tall-deck. If you wish to go with a single-plane, we found a few choices. First, Dart Manufacturing has a Tall Deck Oval Port single-plane for the Holley 4150 flange carb under PN 41215000. It accepts the standard deck-height distributor. This is a great help, since the stock tall-deck distributors are hard to come by. Next, Holley offers a single-plane Weiand Team G inlet for the oval-port cylinder heads. They have also machined the manifold for standard deck distributors. The Team G manifold is sold under PN 7528.
For your next trick you need to find oval-port manifold spacers. There are many manufacturers that offer rectangle spacers. Jomar Performance Parts offers oval-port spacers in both billet aluminum and Delrin plastic. Delrin is a great heat insulator, which keeps the heat in the cylinder heads and not in the inlet manifold. The Billet spacers are sold under PN 5273, and the Delrin under PN 5253.
Good luck with your torque monster. They can be a lot of fun, especially when you take your friends for a ride and they have to pull the upholstery out of their tail.
Things That Go BumpQ I have a '63 Corvette that is having toe-in/toe-out issues. I checked the front suspension for worn parts; I changed the control-arm bushings (upper and lower) and one outer tie-rod end. What happens is when the front tires are jacked up with no weight on them, the wheels toe-in about 1 inch when the toe-in was set at 11/416-inch toe-in at ride height. Is this normal? I jacked up the front end on my '65 Chevelle and the change is very little. I know the two cars are different, but is that a normal condition for the Corvette? Jae HondaVia e-mail
A Yes, your Vette has an inherent problem with bumpsteer. You only measured your bump when you unloaded the suspension. When the suspension goes to full compression, the front wheels toe-out at least the 1 inch you saw while raising the car. This is an easy 2-plus inches of toe-in to toe-out. This can make for very entertaining high-speed driving.
The toe change in a vehicle is affected by the tie-rod length and angle in relation to the lower control-arm pick-up points. The tie-rod length should be the same as the lower control-arm length from the arm's mounting point to the lower control-arm ball joint. Also, whatever the vertical distance the inter tie-rod height is in relationship to the lower control-arm pick-up point, you should have the same vertical relationship to the lower control-arm ball joint. This will set the tie rod at the same angle as the lower control arm. With these angles and lengths correct, this is a good starting point for the steering. From there you can tune the bumpsteer by raising or lowering the outer tie-rod pick-up point to dial out unwanted bumpsteer.
As you can tell by the differences between your '65 Chevelle and your Vette, the lower control arms are much longer on your Vette. Also, you can see that this isn't a simple adjustment. We did find a complete power rack-and-pinion conversion sold by Car Chemistry. The Steeroids rack conversion is a bolt-in system, in which the inter tie-rod pick-up points have been moved inboard, giving you the ability to adjust the height at the outer tie-rod to tune the bump. The kit comes with all components except for a pump, and can be installed in three hours.